Charpy Impact Test

Specimen Configuration

Preparation of the test bar requires precise dimensions and a controlled notch depth to ensure repeatable results. Because the charpy impact test relies on a specific geometry, any variation in the notch radius will noticeably alter the final energy reading. Moulding conditions used to create the bars must also be standardized to prevent internal stresses from skewing the data.

These bars are typically placed horizontally on supports before being struck by the hammer. Uniformity in the sample thickness is necessary for cross laboratory comparisons. Accurate machining of the notch is the most sensitive part of the preparation.

Energy Absorption

Calculation of the difference between the initial and final height of the pendulum reveals the energy lost to the specimen. A high value in the charpy impact test indicates a material that can deform plastically and dissipate stress effectively. Brittle resins absorb very little energy and shatter into pieces.

Tougher copolymers absorb the bulk of the force through internal deformation.

Standard Compliance

Adoption of international protocols ensures that data is comparable across different laboratories. While the charpy impact test is common in Europe, other regions may prefer different striking geometries. Consistent testing allows a moulder to verify that a new batch of resin meets the original design requirements.